Information profiles were presented on the following organic anhydrides by virtue of their importance in the industrial community: acetic-anhydride (108247), butyric-anhydride (106310), citraconic-anhydride (616024), dodecenylsuccinic-anhydride (25377735), isobutyric-anhydride (97723), maleic-anhydride (108316), phthalic-anhydride (85449), propionic-anhydride (123626), pyromellitic-dianhydride (89327), succinic-anhydride (108305), tetrahydrophthalic-anhydride (85438), and trimellitic-anhydride (552307). The organic anhydrides appeared to be moderately toxic with median lethal dose levels for rats ranging from 697 to 2600mg/kg. The maleic, phthalic, acetic and trimellitic anhydrides appeared to be the most acutely toxic of the group discussed. All were irritants to the skin, eyes, and respiratory tract. Injection site tumors have occurred following administration of succinic and maleic anhydrides. Limited evidence suggested teratogenic potentials for acetic, maleic, phthalic, and succinic anhydrides.